The present invention relates to a recording apparatus, and, for example, to a printing apparatus for drawing out a printing medium wound in a roll shape, and for discharging ink onto the printing medium for printing.
For instance, there is known a large ink jet printing apparatus for recording (printing) characters, images, and the like by discharging ink onto a medium such as a plastic sheet material for an advertising drop curtain for a department store, an advertising signboard, or the like.
In the printing apparatus of this type, a roll (roll paper) wound in a roll shape is mounted, and the roll is rotated in a direction of delivering the medium so as to supply the medium to a printing part on a platen.
Incidentally, the roll itself has a weight of, for example, approximately a few tens to a hundred kilograms. Therefore, if the roll is stored horizontally, the medium may be fixed by its weight.
In this case, it is necessary to deliver the fixed part of the roll to the printing part while the medium is delivered. As a printing apparatus having such a mechanism, there is a “paper release mechanism of a printing apparatus” described in Japanese Patent Application Laid-open No. 2007-268824.
This technology uses a releasing nail that is biased onto a surface of the roll so as to be brought into abutment with the firmly fixed part of a medium.
According to this technology, when the roll having the fixed medium is rotated, the fixed part is not delivered but contacts with the releasing nail so that the medium is released.
However, if the releasing nail is used, a tip of the nail scrapes a print surface of the medium before printing and may damage the print surface.
In addition, if the medium is fixed strongly, the releasing nail cannot release the medium. Even if possible, it is necessary to increase a force of pressing the releasing nail to the roll, which may increase a scratch on the surface of the medium.
In addition, it is necessary to change a position of setting the releasing nail in accordance with a direction of winding the roll (inside roll or outside roll), and hence it takes time to set the releasing nail.